1. Field of the Invention
This invention relates in general to downhole well pump motors and in particular to systems for cooling and protecting downhole motors for pumps or compressors in petroleum production wells.
2. Description of the Prior Art
Generally, well pump motors for downhole use are surrounded by a sealed motor housing that is filled with a fluid that helps to cool the motor components and that helps to prevent exterior fluids from entering the motor housing. In some applications, however, the heat dissipation away from the motor housing is not sufficient to prevent overheating of the motor. For such applications, improved cooling systems are required.
Electrical motors for surface application have used vanes or ribs extending from the motor housing to increase the heat transfer surface area, thus providing enhanced cooling. Oil and gas wells however, are fairly small in diameter and thus lack space for large fins. U.S. Pat. No. 4,126,406 shows a system for a downhole well pump motor which uses a surface pump to pump water, or other cooling fluid, down an insulated tubing to a shroud located around the motor housing and up a return tubing to a cooling system at the surface. Such a system requires a surface pump, heat exchanger, and additional tubing, adding considerably to the cost.